The present invention relates generally to a medical proton therapy facility and, more particularly, to a medical synchrotron having strong focusing, rapid cycling and fast extraction capabilities.
It has been known in the art to use a synchrotron and gantry arrangement to deliver proton beams from a single proton source to one of a plurality of patient treatment stations for proton therapy. For example, U.S. Pat. No. 4,870,287 to Cole et al. discloses a multi-station proton beam therapy system for selectively generating and transporting proton beams from a single proton source and accelerator to one of a plurality of patient treatment stations each having a rotatable gantry for delivering the proton beams at different angles to the patients. A duoplasmatron ion source generates the protons which are then injected into an accelerator at 1.7 MeV. The accelerator is a synchrotron containing ring dipoles, zero-gradient dipoles with edge focusing, vertical trim dipoles, horizontal trim dipoles, trim quadrupoles and extraction Lambertson magnets.
The beam delivery portion of the Cole et al. system includes a switchyard and gantry arrangement. The switchyard utilizes switching magnets that selectively direct the proton beam to the desired patient treatment station. Each patient treatment station includes a gantry having an arrangement of bending dipole magnets and focusing quadrupole magnets. The gantry is fully rotatable about a given axis so that the proton beam may be delivered at any desired angle to the patient.
U.S. Pat. No. 4,992,746 to Martin discloses an ion therapy system including a pre-accelerator and a rapid cycling synchrotron. The system may be used for proton therapy whereby a proton beam is extracted from the synchrotron and injected into a storage ring by fast extraction using a kicker magnet and a septum magnet. The pre-accelerator includes a LINAC that produces protons at energies of the order of 50 MeV.
U.S. Pat. No. 5,382,914 to Hamm et al. discloses a proton-beam therapy LINAC including a secondary stepped frequency drift tube LINAC (DTL) in addition to a radio-frequency-quadrupole (RFQ) LINAC for acceleration of low-peak-current proton beams. The DTL accelerates the proton beam from 12.5 MeV to 70.4 MeV over a length of 7.92 meters. U.S. Pat. No. 5,001,438 to Takanaka discloses a beam supply device for use in a patient therapy system. The device includes a rotatable switching magnet for directing a particle or radiation beam to one of several patient treatment stations arranged around the rotatable switching magnet. A rotatable switching magnet is provided, which eliminates the need for a switchyard with multiple switching magnets.
It would be desirable to improve upon the prior art medical proton therapy facilities by providing many pulses of beam per second, faster beam extraction, stronger beam focusing and more rapid cycling, while at the same time permitting irradiation by multiple particle species.